Re: [Frameworks] B+W Handprocessing Reversal Bleach?

From: Ed Inman <edinman_at_earthlink.net>
Date: Tue, 4 Oct 2011 15:36:38 -0500 (GMT-05:00)
The Ilford formula is published here: http://www.ilfordphoto.com/Webfiles/20061291034093.pdf
The permanganate bleach formula is suitable only if continuous agitation is possible. If you are using a rewind tank like the G3 you must use dichromate bleach.
If reversing an old school emulsion like Efke cut the amount of permanganate in half for solution A (with Solution B unchanged) and ALWAYS use a hardening fixer after the second development.
All of the chemicals are generally available on ebay in bulk.
As an alternative to concentrated sulphuric acid you can use standard battery acid available from most auto parts stores. Mix at a rate of roughly 7.5 ounces to one gallon to make solution B.
As an alternative to Ilford developers Kodak D-19 is generally suitable.
Ed
-----Original Message-----
From: edwin m
Sent: Oct 4, 2011 2:36 PM
To: frameworks_at_jonasmekasfilms.com
Subject: Re: [Frameworks] B+W Handprocessing Reversal Bleach?


i don't think there's an off-the-shelf solution without potassium dichromate or permanganate. foma kits use dichromate and ilford uses permanganate. out of those two, permanganate is considered the safer.

it's also worth saying that potassium ferricyanide might not be any less toxic (its use is linked to cyanide poisoning). if you do use it, apparently 10g in 500ml water will do for the bleach, and then 100g sodium sulphite in 500ml water for the clearing bath. don't let acid anywhere near, or it'll give off a lot of cyanide gas

hope some of that's useful

edwin



> Date: Tue, 4 Oct 2011 14:47:26 -0300
> From: marcia.l.connolly_at_gmail.com
> To: frameworks@jonasmekasfilms.com
> Subject: [Frameworks] B+W Handprocessing Reversal Bleach?
>
> Hello all I'm teaching Experimental Film at NSCAD and we are
> hand-processing in a communal darkroom and there is a concern about
> our bleach. Does anyone know what the least toxic recipe for a 3374
> Hicon B+W reversal bleach is? One that does not use P. Dichromate or
> Permanganate?
>
> Has anyone tried a Potassium Ferricynide based bleach?
>
> Any help would be appreciated.
>
> Marcia Connolly
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> FrameWorks@jonasmekasfilms.com
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Received on Tue Oct 04 2011 - 13:36:49 CDT